A sermon about Joe Theismann and the Over The Hill Gang, on style versus substance, follows this safety blitz from the National Football League.

The NFL has been preaching parity louder than farmers for some time-but the familiar teams continued to dash into the AFC playoffs and limp into the NFC playoffs. Now the meek are beginning to slay the mighty.

As everyone anticipated, the NFC wild-card game is for the birds, the Falcons against the Stabler and Bert Jones. Al Davis and George Allen. Or the Packers having a chance to win their divisional championship until the final quarter of the final game.

Or the Saints winning seven games.

This sort of thing is supposed to happen, because the NFL penalizes excellence, with its schedule, and rewards incompetence, with its draft. Only the very best teams avoid stretches of mediocrity. The AFC Central Division shows that anyone can win if he waits long enough.

Think back to 1970. Remember the worst division in the league? Of course, the AFC Central. The 8-6 Bengalis won the title; Cleveland wa 7-7, Pittsburgh 5-9 and Houston 3-10-1.

At the moment, the AFC Central is the strongest division in the league.

Like their basketball counterparts, pro football teams search for mismatches, ways to allow what they do best to overcome their weakness. When Washington's defense and Oakland's offensive line and quarterback began to erode, it exposed existing problems-and later compounded them.

The Oilers will go as far as Earl Campbell's legs take them, the Dolphins will ride Bob Griese's arm. The defensive line determines the Cowboy's fate and the Bronco tacklers try to carry their quarterbacks into the Super Bowl once again.

The Steelers have enough players and enough incentive to win their third Super Bowl in five years; the Vikings together win both NFC wildcard teams could not muster an all-star team that would be favored over the Cowboys.

Leverage and cycles, perhaps the most important terms in the NFL. Leverage can be an area or an entire unit, sometimes a single player. Or a personnel director. Or a coach's min dand personality.

In the final 10 games for the Redskins, the 2-8 slide that became swifter each week, one player had the chance to be heroic, to realize the rich dreams that have fired him for so long.

Some quarterbacks are able to make ordinary teams good, to outmaneuver bad blocking or pass quickly enough and accurately enough to generate points under adverse conditions.

Theismann had that chance-and failed.

This is not to dismiss Theismann as a factor in the future; it is meant to suggest that he is not likely to rise above the level of his teammates for some time, if ever.

Athletically and financially, Theismann has spent most of his eight-year pro life searching for shortcuts. He wrote a how-to book about quarterbacking before throwing a pass in the NFL. He was a Washington television regular and doing sundry endorsements before becoming the Redskin's starter.

Drafted on the fourth round by the Dolphins in 1971, he tried to avoid a long apprenticeship behind Griese by skipping to Canada. When Sonny Jurgensen's and Billy Klimer's combined ages reached 75-in 1974-Thiesemann joined the Redskins.

In his 30th year, he had achieved more off the field than on. The final game of his first full season as a regular ended with the ultimate insult, fans who once adored him chanting: "We want Billy."

Part of what plagues Theismann is bound to smack anyone who replaces a vintage Redskin. He looks like a football player, so too much is expected too soon.

That was the endearing part of George Allen's Redskins. The halfback could scarcely hear out of one ear, the quarterback could barely walk and the center had more surgery than the Soviet economy.

The left defensive end looked like the ultimate prize in a carney ring toss, the left linebacker beat cancer and the left cornerback fit the classic Adolph Rupp generalization: "A Shetland pony in a stud-horse parade."

Allen encouraged this, for it fueled already quick self-motivators. But it showed the folly of first impressions, because every one of those players was wonderfully gifted.

Of Allen's players, a half dozen-or Sonny Jurgensen, Charley Taylor, Larry Brown, Jack Pardee, Len Hauss and Pat Fischer-left the game with Hall of Fame nominations all but secure.

If there was a section in the Hall for leadership and single-minded determination, for the ultimate die-on-your-shield attitude in sports, Kilmer's would be the first bust.

Because the ordinary-looking Redskins won so regularly and showed such rare enthusiasm, the false impression was generated that younger, healthier replacements would be better.

The last two months shattered that notion. CAPTION: Picture 1,2,Reflections of a bitter end: Mike Thomas (top), coming off field pained by leg injury and fumble; offensive tackle Terry Hermeling, while Beaars keep Redskin defense on field. Photos by John McDonnell-The Washington Post